不同定义的位涡对四川盆地一次极端暴雨的诊断  

Diagnosis of Different Definitions Potential Vorticity in an Extreme Rainstorm in the Western Sichuan Basin

作　　者：郭云云 康岚[1,2] 邓莲堂 周懿 王晨曦[5] GUO Yunyun;KANG Lan;DENG Liantang;ZHOU Yi;WANG Chenxi(Sichuan Meteorological Observatory,Chengdu 610072,Sichuan,China;Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province,Chengdu 610072,Sichuan,China;National Meteorological Center,Beijing 100081,China;Numerical Weather Prediction Center Of China Meteorological Administration,Beijing 100081,China;Sichuan Meteorological Disasters Prevention Technology Center,Chengdu 610072,Sichuan,China)

机构地区：[1]四川省气象台,四川成都610072 [2]高原与盆地暴雨旱涝灾害四川省重点实验室,四川成都610072 [3]国家气象中心,北京100081 [4]中国气象局数值预报中心,北京100081 [5]四川省气象灾害防御技术中心,四川成都610072

出　　处：《高原气象》2022年第5期1242-1250,共9页Plateau Meteorology

基　　金：国家自然科学基金项目(41275103);中国气象局创新发展专项(CXFZ2021Z033)。

摘　　要：利用NCEP 1°×1°再分析资料、国家级地面自动站观测资料、探空资料和四川加密自动站逐时降水观测资料对2020年8月15-18日四川盆地西部一次极端暴雨的不同定义的位温和位涡进行诊断分析.结果表明:本次暴雨过程属于500 hPa"东高西低"型暴雨,中层低槽、低层切变线和低涡是此次暴雨有利的动力条件.暴雨区上空均存在明显的等θ_(se)和θ*线密集带,但θ较为平直,降水指示性较差.500 hPa和800 hPa附近PV异常区与降水区对应较好;对流层中低层湿位涡MPV1上正下负的叠置以及MPV1、MPV2负值的重合区是强降水发生的警戒区,强降水中心靠近低层MPV1正负值交界处,强降水时段中低层对流不稳定能量占主导作用;800~600 hPa广义湿位涡异常扰动区可作为此次暴雨警示区,它的诊断效果与相对湿度密切相关.单站不同定义的位涡时空演变和降水的时间演变均有较好的对应关系,且降水强度与扰动强度呈正相关.不同的是,PV、MPV和GMPV三者的提示高度分别在650~450 hPa、600~500 hPa和800 hPa左右;而不同定义的位温差异明显,其中低层广义位温θ*分布最能体现强降水高水汽的特点.The data of NCEP reanalysis(1°×1°),national ground automatic stations,radiosonde and Sichuan encrypted automatic stations were used to diagnose the three definitions potential temperature and potential vorticity in an extreme rainstorm which occurred in the western Sichuan Basin during August 15-18,2020.The results indicate that:Rainfall occurs in the‘high east and low west’circulation in the 500 hPa,the low-level shear line and vortex are the favorable dynamic conditions.There is an obvious pseudo-equivalent potential temperature and generalized potential temperature(θ*)gradient in the heavy rain area,but potential temperature is not.Potential vorticity(PV)anomaly area corresponds well to the precipitation area near 500 hPa and 800 hPa.In the mid-low troposphere,the overlapping area of the negative vertical component(MPV_(1)) and horizontal component(MPV_(2)) of moist potential vorticity,and negative MPV_(1) in lower level,positive in higher level are warning areas of the storm.Meanwhile,the rainfall center is close to the negative and positive junction area of MPV_(1),and the rainstorm was mainly affected by convective instability in the low troposphere.The generalized moist potential vorticity(GMPV)abnormal disturbance area in 800~600 hPa can be used as the rainstorm warning area,and its positively correlated with the change of low-level water vapor.The space-time distribution of three definitions potential vorticity and precipitation have a good correspondence in a single station,and the precipitation intensity is positively correlated with the disturbance intensity.The indicated height of PV,MPV and GMPV is 650~550hPa,600~500 hPa and 800 hPa.Three definitions potential temperature has obvious difference,which theθ*can best reflect the high-water vapor of rainstorm.

关 键 词：位温 位涡 相对湿度 极端暴雨 

分 类 号：P458[天文地球—大气科学及气象学]